Afonso IX was a king of Leon who reigned from 1188 to 1230. He is known for his efforts to expand his kingdom and strengthen its power during the Middle Ages. Afonso IX played a significant role in the Reconquista, the campaign to reclaim the Iberian Peninsula from Muslim rule. He was also notable for his support of the Catholic Church and his contributions to the development of Spanish law. Afonso IX established the Siete Partidas, a legal code that influenced future Spanish law. His reign marked a period of cultural and political growth in the region.